The invention pertains to boundary hardening of machine, equipment and apparatus parts, as well as tools. Objects in which its application is possible and expedient are components made of hardenable steels that are exposed to severe fatigue or wear, have a complicated shape, and whose surface must be selectively hardened on the functional surfaces, or in which the functional surface has a multidimensional shape. The invention is particularly advantageous for use in those components, in which the geometry of the functional surface changes three-dimensionally along the component. Such components include large dies, cutting and trimming tools, as well as compression molds for auto body production, turbine blades for the low-pressure part of steam turbines, cam disks, machine beds of tools, etc. Other applications are local heat treatments, like boundary solution annealing, boundary tempering or quenching of geometrically complicated components.